Method of screening solid electrolyte having excellent lithium ion conductivity and stability
Disclosed is a method of screening a solid electrolyte having excellent lithium ion conductivity and stability.
1 . A method of screening a solid electrolyte, the method comprising:
preparing a population by extracting a crystallographic information framework (CIF) of a compound comprising a specific element from a crystallography open database (COD) or an inorganic crystal structure database (ICSD);
screening a first group comprising compounds for which a site occupancy of the specific element in a unit cell is not 1 among the population;
screening a second group comprising compounds satisfying Condition 1 below among the first group;
preparing a third group by substituting each element of the compounds included in the second group with another element belonging to a same group of a periodic table, wherein the specific element is substituted with a lithium (Li) element; and
screening compounds satisfying Condition 2 below among the third group:
[Condition 1]
Compound in which a mean square displacement of the specific element is 30 Å 2 or greater than 30 Å 2 ,
[Condition 2]
Compound in which a maximum framework displacement of an element in a unit cell is less than 50 Å.
2 . The method of claim 1 , wherein the specific element comprises silver (Ag) or copper (Cu).
3 . The method of claim 1 , wherein the mean square displacement of the specific element in Condition 1 is determined using Equation 1 below:
Mean
square
displacement
of
specific
element
=
<
[
r
(
t
)
]
2
>=
1
N
∑
i
<
[
r
i
(
t
+
t
0
)
]
2
-
[
r
i
(
t
0
)
]
2
>
[
Equation
1
]
wherein N is a number of the specific element (i) in a unit cell, t is a unit time, r i (t+t 0 ) is a displacement of the specific element (i) after a unit time has elapsed, and r i (t 0 ) is an initial position of the specific element (i).
4 . The method of claim 1 , wherein the maximum framework displacement of the element in the unit cell in Condition 2 is determined using Equation 2 below:
Maximum
framework
displacement
of
element
in
unit
cell
=
max
[
D
i
]
[
Equation
2
]
D
i
=
d
i
(
Δ
t
)
-
∑
i
=
0
n
d
i
(
Δ
t
)
n
wherein d i (Δt) is a displacement of an element (i) in a unit cell at a given time (dt), and n is a total number of elements in the unit cell.
5 . The method of claim 1 , further comprising screening compounds satisfying Condition 3 below among the compounds satisfying Condition 2:
[Condition 3]
Compound having a relative displacement of less than 1,
wherein the relative displacement is determined using an equation
Relative
displacement
=
max
(
MSD
fi
MSD
mi
)
,
in which MSD mi is a mean square displacement of a lithium (Li) element and MSD fi is a mean square displacement of an element in a unit cell.